CyanogenModXT720/android_frameworks_base — comment on commit 964bb20ffd89a168753e09fe810e417eb33a939b
File:  line 0
By peshovec:

If You mean that in the above case if dimensions are 1280x720 they are remapped to surprise 1280x720 :)

....
static const camera_size_type preview_sizes[] = {
{ 1280, 720 }, // 720P
{ 768, 432 },
};
....

which obviously is pointless, you are absolutely correct:)

it was for fast testing, i plan to remap to something else with almost the same aspect ratio.

in my testing overlay-ing to 1280x720 works, but can't focus properly... so further testing will be with something different (picked from a list of the "possible" values preview-size-values=176x144,320x240,352x288,640x480,720x480,720x576,800x448,848x480,1280x720) with about 1.77777 aspect ratio. If that helps focus (as wide 848x480 seems to focus very well), will dig around the same about still pictures (in my opinion they are all slightly out of focus)

of course (at least for now) all that is just speculation, based on theory that focusing is based on the contrast of the displayed "overlay-ed" picture